Jennifer Aniston and Justin Theroux Seemed Ready to Tie the Knot - But Now There's No Date in Sight. Why the Pair Are Taking It Slow

Very little black dress? Check. Friends to laugh with? Check. Toned arms, tanned legs? Check and check. Fiancé by her side? Not so fast ... At the Spike TV Guy's Choice Awards on June 8, Jennifer Aniston may have been flying solo without spouse-to-be Justin Theroux, but that didn't mean marriage was off her mind. Taking the mic to playfully jab honoree Jimmy Kimmel, with her supersize diamond ring from Theroux on full display, Aniston cheekily acknowledged the obsession with her marital status. "Like me, you got engaged this year," she addressed Kimmel in front of the crowd. "Unlike [with] me, nobody cares."

In the 10 months since their August 2012 engagement, all eyes have been on Aniston, 44, with fans wondering just when she will become Mrs. Theroux. But multiple sources in contact with Aniston and her inner circle (who spoke anonymously to protect their relationships with the actress) say that plans for the much-anticipated wedding, under way earlier this year, appear to have stalled. As of a few months ago, "wedding bands were designed, and Jen was deciding on a dress," says an insider who speaks to Aniston often. "She was so happy to be planning." Aniston had picked a date too, for a spring affair, this source claims. A second source, who frequently works with Aniston, confirms that earlier this year, "her team was trying to clear her schedule for a spring wedding." Now, as weeks pass, Aniston and Theroux, overloaded with work commitments and a time-consuming home renovation, have put arrangements for their big day on the back burner. At the moment, says the insider, "there is no new wedding date."

Of course Aniston is a pro at keeping people guessing. And she has told friends her ideal wedding is a low-key one with a small group of friends and family - not hard to plan very quietly. "Just be yourself," she told PEOPLE of her wedding-day philosophy last fall, calling Theroux, 41, "a beautiful partner." So why haven't they sealed the deal yet? One reason could be that their careers and their massive home overhaul have taken priority. In January 2012 Aniston bought a $21 million, 8,500-sq.-ft. Bel Air estate she hoped to transform into the couple's dream abode. Eighteen months later the home has a 2,000-sq.-ft. addition, a new guest house, a pool area with black lava veneers and a pizza oven. But it's still not finished. "With all the work on the house, they just thought it was too much to plan a wedding as well," says the insider. "So they decided to step back and just focus on the house." (Some sources have hinted it could be a wedding venue.) Aniston and Theroux, who had been holing up at a nearby hotel, have spent a few nights there. "They can't wait to move in [fully]," says the insider. "They're eager to get the house all ready."

But the couple may have missed their window for a leisurely wedding and honeymoon. They're both juggling major upcoming projects through at least early August (see box). While Theroux tackles an HBO pilot, Aniston will promote We're the Millers, out Aug. 9, in which she plays a stripper. "She was game to do it. Jen is really brave with the parts she has been choosing lately," says director Rawson Marshall Thurber. And soon she'll film Squirrels to the Nuts with veteran director Peter Bogdanovich, who calls her "just terrific. She really knows comedy."

Comedy, of course, is what first drew the sunny California girl and the tattooed New Yorker together: They met on the set of Wanderlust and started dating in May 2011. Merging their two worlds has brought them a lot of joy - and challenges that could also be leading them to consider the next step with caution. "They're complete opposites," the insider says. "Justin is laid-back, while Jen gets more worked up. But Justin made her more Zen." Still, some in their circle question whether Theroux is ready to give up his New York City lifestyle and his circle of friends there for an L.A.-based existence. "Justin has never seemed very comfortable in L.A.," says the insider. "They love each other, but they need to figure out a way to create a life that makes them both happy."

A source who knows the couple professionally cautions that the lack of a wedding date isn't an indication that anything is amiss. "Jen has a very happy life and doesn't want that to change," says the source. "There are other priorities [besides marriage]. She's very busy." But the insider says that Aniston is ready to say "I do" whenever the timing is right: "Jen is crazy about Justin. And she can't wait to be his wife."